ITB Expert Warns of Aftershock Risk in NTT

Professor Irwan Meilano, a leading earthquake and cadastre expert from the Faculty of Earth Sciences and Technology at Bandung Institute of Technology, has said the magnitude 7.7 earthquake that struck East Nusa Tenggara on Saturday occurred along the Flores back-arc thrust fault. He cautioned that aftershocks remain possible because parts of the fault have not yet produced an earthquake.

He said the earthquake location forms part of the Flores back-arc thrust fault and has significant seismic activity. The area previously experienced a magnitude 6.6 earthquake in 2009 and a series of earthquakes north of Lombok in 2018.

Professor Irwan said academic studies used in compiling the national earthquake map indicate that parts of the region still hold seismic potential. “There are still parts that have not actually produced an earthquake. We do not hope that will happen,” he said on Sunday.

However, academic research produced by the National Centre for Earthquake Studies shows that potential remains in the area. He said aftershock activity is one of the matters requiring attention after the main earthquake.

Professor Irwan said large earthquakes are generally followed by aftershocks whose magnitudes tend to decline gradually. Even so, public vigilance remains necessary.

He reminded that the experience of the 2018 Lombok earthquakes showed that seismic activity can involve adjacent segments. “It is very possible, though we do not hope for it, that this earthquake could then trigger an adjacent segment,” he said.

He also cautioned that aftershocks above magnitude 6 still have the potential to cause significant impacts. “There may be many earthquakes, but over time they become smaller. However, there is still a possibility, albeit small, that if an earthquake exceeds magnitude six, it could cause quite significant damaging impacts,” he said.